Silicone compounds which have organic functional groups have been used in a wide variety of fields as organic resin modifying agents, surfactants and fiber treatment agents, etc. In particular, in cases where such compounds are used as organic resin modifying agents, when these compounds are used as one raw material of a so-called "copolymer" in which a silicone compound is incorporated into an organic resin molecule, it is necessary to select organic functional groups that are copolymerizable with the organic resin. For example, in cases where the organic resin is a resin that is obtained mainly by polycondensation, such as a polycarbonate resin, an organopolysiloxane which contains hydroxyphenyl groups is generally used as the modifying agent. Polycarbonate resins in which siloxane units are incorporated into the principal chains (see Japanese Patent Application Kokai No. Hei 3-79626), and polycarbonate resins formed by graft-bonding siloxane chains for the purpose of achieving a greater increase in the degree of freedom of movement of the organopolysiloxane chains (see Japanese Patent Application Kokai No. Hei 5-155999 and Japanese Patent Application Kokai No. Hei 7-165897) have been proposed as polycarbonate resins modified by organopolysiloxanes. However, since these silicone-modified polycarbonate resins are polymers in which the organopolysiloxane chains in the molecules are rich in flexibility, such polycarbonate resins have a low glass transition temperature; As a result, if these materials are used in molding, there is a drop in the glass transition temperature and hardness of moldings. Furthermore, the drawbacks of inadequate mold release characteristics and water-repellent characteristics have also been encountered.
Meanwhile, in regard to silalkarylene compounds, polymers which have silmethylenephenylenesiloxane units expressed by the formula: ##STR2## in the molecular chains are known (see High Temperature Siloxane Elastomers, Chapter IV, p. 215-231); however, silalkarylene compounds which have hydroxyphenyl groups on both ends are unknown.